The invention relates to a trailer coupling for motor vehicles, comprising a bearing part arranged fixed to the vehicle and a pivotal part mounted on the bearing part and having a ball neck and a coupling ball, the pivotal part being pivotal in relation to the bearing part about an axis between a rest position and an operative position.
A trailer coupling of this type is already disclosed by German patent application 196 12 959.1.
In a trailer coupling of this type, a self-locking gear for driving the pivotal movement is provided and at the same time also allows the ball holder to be fixed in any position. An automatically locking gear of this type is complex structurally, from the point of view of the required safety standards, and thus also from a manufacturing point of view.
The object of the invention is therefore to provide a trailer coupling of the generic type such that it may be fixed in the operative position securely and simply.
This object is achieved with a trailer coupling of the type described at the outset in accordance with the invention in that the pivotal part has two abutting elements arranged spaced from one another, in that the bearing part is provided with two supporting elements and in that, to fix the ball neck in the operative position, one of the supporting elements and one of the abutting elements co-operate such that the ball neck undergoes a pivotal movement in a first direction which is countered by the other of the supporting elements and the other of the abutting elements, and in that in so doing the abutting elements and the supporting elements are able to abut against one another without play.
The advantage of the inventive achievement can be seen in the fact that by providing two co-operating pairs of abutting elements and supporting elements there is the possibility of these abutting against one another without play in pairs and hence achieving fixing of the pivotal part relative to the bearing part which is permanently without play and thus also permanently low in wear, it having been found that, as a result of the abutting against one another without play of the co-operating pairs of one of the abutting elements and one of the supporting elements, it is possible to achieve extremely low wear in the region thereof and thus also in the fixing of the pivotal part.
It is particularly advantageous in this connection if, to fix the ball neck in the operative position, the abutting elements and the supporting elements can be tensioned against one another in a clamping position, the additional tensioning against one another of the pairs of one of the abutting elements and one of the supporting elements providing the possibility of ensuring that there is no play even in the event of material deformation resulting from peak loads occurring, and thus also the possibility of achieving the minimum of wear even when the pivotal part is fixed relative to the bearing part.
It is particularly favourable in this connection if, in the clamping position, one element of a pair comprising one of the supporting elements and one of the abutting elements acts on the other element in the direction in which the clamping force acts, in such a way as to provide an adjustment. The advantage of this way of achieving the object is to be seen in the fact that on the one hand the action of the force makes it possible for the supporting elements and abutting elements to be tensioned against one another and on the other hand the adjustment of at least one element has the effect that, if the other element were to yield because of material resilience when a peak load occurs in the direction of the clamping force action, the one element still maintains the clamping force action on the other element as a result of the former""s adjustment, and thus, in the event of a resilient deformation in the region of the pivotal part and the bearing part and/or the pair of the other of the supporting elements and the other of the abutting elements and hence a limited yielding of the other element, the action of the force and the absence of play is still maintained in all supporting elements and abutting elements.
In a particularly favourable manner, the action of the force of one element of a pair comprising one supporting element and one abutting element can be achieved in that in the clamping position a resilient clamping force energy store acts on one of the elements.
This is particularly favourable if the resilient clamping force energy store is constructed as a spring force energy store.
Furthermore, the adjustability of the one element can be achieved in a particularly favourable manner if the latter is mounted movably in the clamping direction.
A movable mounting of this type of one of the elements can be achieved either by a linear mobility thereof or using a linear mobility of the element which is derived from a rotary movement.
No precise details have yet been given regarding the mobility of the abutting elements. Thus, an advantageous example embodiment provides that when the pivotal part is pivoted about the axis each of the abutting elements rotates about the pivot axis on a radially spaced path. This means that it is not necessary to give the abutting elements their own mobility, but rather the abutting elements can be connected directly to the pivotal part and be arranged to be pivotal therewith.
It is particularly favourable in this connection if the abutting elements rotate about the pivot axis on different paths, that is to say if each of the abutting elements has its own path by means of which it rotates about the pivot axis. From a spatial point of view, this means that a particularly simple assignment of the individual abutting elements to the supporting elements corresponding thereto can be achieved.
In principle, it is conceivable to make the abutting elements additionally movable relative to the pivotal part as well, for example in order to achieve the abutting against one another without play of the abutting elements and the supporting elements. However, it is particularly simple from a structural point of view if a first one of the abutting elements is constructed as an element arranged fixed to the pivotal part.
It is even more advantageous if the second of the abutting elements is also constructed as an element arranged fixed to the pivotal part.
In order to achieve the maximum possible lever arm between the axis about which the pivotal part is pivotal and the respective abutting element, that is to say the activation of the force acting on this abutting element, it is preferably provided that one of the abutting elements is arranged on a comb of the pivotal part, this comb having a greater spacing from the pivot axis than for example a bearing body of the pivotal part which surrounds a pivot pin.
In order also to exploit the fact that the ball neck extends away from the pivotal part and thus necessarily extends at an increasing radius from the axis, it is preferably provided that another of the abutting elements is arranged on a lug of the ball neck, this lug adjoining the pivotal part.
Similarly, no further information has yet been given in the explanation of the individual example embodiments regarding the arrangement of the supporting elements themselves. Thus, an advantageous example embodiment provides that a first one of the supporting elements is arranged in a region of the bearing part which is at the rear, as seen in the direction of travel.
Furthermore, in an example embodiment it is preferably provided that a second of the supporting elements is arranged in a region of the bearing part which is at the front, as seen in the direction of travel, while in another example embodiment the second supporting element is also arranged in the rear region of the bearing part.
As regards the mobility of the supporting elements, the greatest variety of ways of achieving the object is conceivable. For example, it is conceivable to move both supporting elements in the direction of the abutting elements, or both abutting elements in the direction of the supporting elements.
A way of achieving the object which is particularly preferred because of its structural simplicity in this connection provides that one of the supporting elements is arranged on the bearing part as a supporting element which at all times projects into the path of the corresponding abutting element and thus for example is acted upon by the abutting element whenever the latter is in the operative position.
In order, however, to have the simultaneous possibility of being able to pivot the ball neck out of the operative position into the rest position and back again, it is preferably provided that another of the supporting elements is arranged on the bearing part as a supporting element which is movable from a release position into the path of the other abutting element as far as a locking position and vice versa.
As regards the mobility of the supporting element from the release position into the locking position, the greatest variety of possibilities is conceivable. One way of achieving the object provides that the movable supporting element is movable into the path of the abutting element as a result of a linear displacement.
Another preferred embodiment provides that the movable supporting element is capable of being pivoted into the path of the corresponding abutting element.
No precise details have yet been given regarding the overall mobility of a supporting element which is movable relative to the path of the corresponding abutting element between a locking position and a release position. Thus, an actuating means is preferably provided for the supporting element, and this serves to provide a bearing for the supporting element for these movements and to act upon it.
One embodiment of an actuating means of this type comprises an adjusting wedge in order to move the supporting element, which is guided movably in a guide, between the locking position and the release position.
Another advantageous way of achieving the object provides that the actuating means comprises a pivot bearing and a pivot drive for the movable supporting element.
No precise details have been given regarding the possibility of causing the supporting surfaces to abut against the corresponding abutting surfaces and to be tensioned against one another in this position, as regards the possibility of implementing such a tensioning with the example embodiments described hitherto. Thus, an advantageous example embodiment provides that a tensioning gear is provided to tension the abutting elements and the supporting elements against one another, by means of which tensioning gear at least one of the supporting elements or at least one of the abutting elements is movable out of a free position into a clamping position and vice versa.
A tensioning gear of this type can be constructed in the greatest variety of ways. For example, the tensioning gear could be constructed such that it can be moved even during the reaction force acting thereon during tensioning of the abutting elements and supporting elements against one another out of the tensioning position, in opposition thereto in the direction of the free position.
However, it is particularly favourable, in particular in order permanently to prevent play from occurring, if the tensioning gear is constructed to be automatically locking, so that the reaction force of the mutually abutting abutting elements and supporting elements cannot result in the tensioning gear moving in the direction of the free position as a result of the action of this force.
A simple possibility for implementing the tensioning gear would be that the tensioning gear is constructed as a wedge gear. A wedge gear represents the simplest way to implement a tensioning gear, in particular if the latter is to be constructed such that it is automatically locking.
In a manner which is particularly simple from a structural point of view, a wedge gear which is constructed as a displacement wedge gear can be implemented.
Another possibility of implementing a tensioning gear is to construct the tensioning gear as an eccentric gear, since an eccentric gear has the advantage that it can be actuated in a simple way by a lever action.
In this connection, the eccentric gear can also be constructed such that it is automatically locking.
No precise details have yet been given regarding the action of the tensioning gear when the abutting elements and supporting elements are tensioned relative to one another. Thus, it is for example conceivable to move both tensioning elements or both supporting elements relative to one another using the tensioning gear, thus towards one another or away from one another using a tensioning gear.
For example, this would also be possible in that a relative movement, made possible by the clamping gear, between the unit comprising the pivotal part and the ball neck and the bearing part is enabled by the tensioning gear.
For example, this could be implemented by constructing the bearing pin of the pivotal part as an eccentric pin and using this eccentric pin to make it possible to tension the abutting elements relative to the supporting elements.
Another way of implementing it would be to move one of the abutting elements relative to the corresponding supporting element.
However, it is particularly favourable, since the supporting elements are arranged on the bearing part, if one of the supporting elements is movable by the tensioning gear in the direction of the corresponding abutting element.
In the case of a wedge gear, in particular a displacement wedge gear, this means that a clamping wedge co-operates with the supporting element in order to move the latter from the free position into the clamping position.
In the case of an eccentric gear, this can be implemented in that the eccentric gear acts on one of the supporting elements and displaces the latter in the direction of the corresponding abutting element.
For example, this could be implemented in that the supporting element, which in any case can be moved into or out of the path of the corresponding abutting element, is also mounted such that it is movable by the eccentric gear.
A solution which is particularly favourable from a structural point of view is one in which the movable supporting element is mounted such that by way of the eccentric gear on the one hand it is displaceable to perform a clamping movement and on the other hand it is pivotal on the eccentric gear in order to pivot into or out of the path of the corresponding abutting element.
An advantageous embodiment provides that the eccentric gear has a pivotally mounted shaft and a pivot bearing for the supporting element which is arranged eccentrically with respect to this shaft, this pivot bearing allowing the supporting element to be pivotal from the locking position into the release position and vice versa.
It is particularly favourable if the actuating means also includes the tensioning gear, so that when the actuating means is operated it is not only possible to move the supporting element between the locking position and the release position but it is also possible to move the latter from the clamping position into the free position and vice versa.
A preferred embodiment of an actuating means of this type provides that in order to fix the pivotal part in the operative position the actuating means moves the movable supporting element from the release position into the locking position, and once the locking position has been reached transfers the tensioning gear from the free position into the clamping position and, in order to release the pivotal part, transfers the tensioning gear from the clamping position into the free position and then moves the supporting element from the locking position into the release position.
Preferably, the actuating means is constructed such that it forcibly moves the movable supporting element from the release position into the locking position and in particular also vice versa.
Furthermore, it is advantageous if the actuating means also forcibly moves the tensioning gear from the free position into the clamping position and in particular also vice versa.
All forcible movements have the advantage that they make it possible to ensure that actuating the actuating means also ultimately results in achieving the desired end position as well.
In particular, a forcible action is also advantageous if it is possible to move from the clamping position to the free position so that it is also possible to overcome jamming of the respective supporting element.
The trailer coupling according to the invention can be actuated particularly easily if the actuating means has a single drive element on actuation of which the movable supporting element can be brought into any of the positions comprising the release position, the locking position, the free position and the clamping position.
One possible way of achieving the object provides that the actuating means has two wedge elements which can successively be brought into a position acting on the supporting element, for example one of the wedge elements serving to transfer the supporting element from the release position into the locking position and the other of the wedge elements serving to transfer the supporting element from the free position into the clamping position.
One alternative to this provides that the actuating means has a ratchet mechanism by means of which it is possible to couple the actuation of the tensioning gear to the pivotal movement of the supporting element between the release position and the locking position.
In order to generate the necessary force to operate the actuating means in order to reach the locking position and the clamping position, preferably a clamping force generating unit which co-operates with the actuating means and acts on the actuating means with a force in such a manner that it is actuated in the direction of the locking position of the supporting element and the clamping position of the tensioning gear is provided.
The advantage of this way of achieving the object is that as a result of the force the actuating means is constantly acted upon in such a way that it has a tendency to move into the locking position and even beyond this into the clamping position, so that the trailer coupling at all times automatically has a tendency to move into a position which securely fixes the ball neck as soon as the latter is in the operative position.
Preferably, in this connection the clamping force generating unit is constructed such that it has a force energy store which acts on the actuating means in order to reach the locking position and the clamping position and which has to be countered in order to reach the free position and the release position.
In order to provide additional security against the trailer device becoming free and in particular against the supporting element being removed from the locking position, it is preferably provided that the clamping force generating unit is provided with a blocking device which, when the latter is not actuated in order to counter the clamping force energy store, blocks leaving of the locking position in the direction of the release position.
Preferably, in this connection the blocking device is constructed such that it has to be freed first before there is any possibility of countering the clamping force energy store.
A particularly advantageous structural way to achieve the object provides that the blocking device can be freed when the clamping force generating unit is actuated in order to reach the release position, and so a movement of this type in the direction of the release position is automatically possible when the clamping force generating unit is actuated.
In order to make operation of the clamping force generating unit as advantageous as possible, it is preferably provided that the clamping force generating unit has an operating element by means of which first the blocking device can be freed and then it becomes possible to act on the actuating means using an unlatching force.
This embodiment of the clamping force generating unit provides the possibility of providing an additional security against freeing the movable supporting element from the locking position.
No precise details have yet been given regarding the arrangement of the actuating means on the bearing part in connection with the explanation hitherto of the individual example embodiments. For example, it is conceivable for the different elements of the actuating means to be borne in different ways, for example on the bearing part.
A particularly favourable solution, however, provides that the actuating means and the movable supporting element form a module which is mountable as a whole on the bearing part.
The fact that a separate module which is to be mounted on the bearing part and is independent thereof is provided also provides the possibility of arranging the actuating means adjustably on the bearing part together with the movable supporting element, so that the possibility is provided of carrying out an adjustment of the actuating means simultaneously with the mounting thereof and therewith carrying out an adjustment of the supporting element held thereby in relation to the supporting element.